1. Field of the Invention
The present invention relates generally to a ratchet screwdriver, and more particularly to a ratchet screwdriver with a rotary positioning structure.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
The ratchet screwdriver is exclusively designed such that the shaft lever could be positively driven (otherwise in an idle state), or reversely driven (otherwise in an idle state), or driven in both directions. The multiple drive modes are implemented through a rotary positioning structure for the ratchet screwdriver.
For the rotary positioning structure of a typical ratchet screwdriver, Taiwanese patent bulletin No. 500022 refers to “an improved structure of a ratchet screwdriver (one)” by the present inventor. FIG. 1 of the bulletin depicts the rotary positioning structure of the typical ratchet screwdriver. The shaft lever 10 for the screwdriver permits the body 11 to be screwed into central axle hole 13 through the pigeon hole 12. The leading edge of gear 14 of the shaft lever 10 is limited by inserting a spacing board 16 into an embedding groove 15 from the bottom of the body 11, such that the shaft lever 10 cannot slide. In addition, the body 11 is fitted with a tube shell 17, and a toggle button 18 is positioned between stop plates 19 and the preset mounting hole 21 of the tube shell 17, such that the toggle block 22 on top of toggle button 18 can be fixed into the mounting hole 21.
The following problem is observed from such typical structure during applications. The shaft lever 10 is fixed by two stop plates 19 and a spacing board 16. Yet, these two stop plates 19 are laterally placed at the gear 14 of the shaft lever 10, and the stop plates 19 are abutted with the gear 14 only through a flange of the plate. Thus, another spacing board 16 shall be designed, and an embedding groove 15 shall be placed at the bottom of the body 11 for insertion of the spacing board 16. But, the shaft lever 10 cannot be fixed stably. So, the positioning structure of shaft lever 10 for the typical ratchet screwdriver still lacks robustness.
Another problem is that the switching of a typical ratchet screwdriver is achieved through the slide of the toggle block 22 in order to control the swaying state of two stop plates 19. However, the switching distance of three modes (positive, reverse and bi-directional) is extremely short (approx. 5 mm) due to the short motion of brake disc 23 of toggle block 22 on the stop plate 19. In such case, it often leads to stronger application of force and excessive toggling, so the user has to adjust its force to achieve the switching.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement in the art to provide an improved structure that can significantly improve efficacy.
To this end, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.